Killing of Tahir Elci during a chaotic gunbattle in Diyarbakir sets off protests; called a tragic accident by officials and an assassination by activists

ISTANBUL—A prominent human-rights lawyer was shot dead on Saturday after wrapping up a news conference in which he had appealed for calm, sparking fresh protests across the country and clouding efforts to bring a halt to continuing violence in Turkey’s Kurdish southeast.

Tahir Elci, one of the country’s best-known advocates for Kurdish rights, was shot in the head during a chaotic gunbattle in Diyarbakir, the de facto capital for Turkey’s Kurdish minority, which broke out after the killing of a policeman. It was unknown...